Ebook Self assessment and review ENT (7/E): Part 1

Part 1 book Self assessment and review ENT has contents: Anatomy of ear, assessment of hearing loss, lesion of cerebellopontine angle and acoustic neuroma, rehabilitative methods, glomus tumor and other tumors of the ear, anatomy and physiology of nose,... and other contents.

Seventh Edition

SAKSHI ARORA HANS

Faculty of Leading PG and FMGE Coachings

MBBS “Gold Medalist” (GSVM, Kanpur) DGO (MLNMC, Allahabad)

India

Self Assessment and Review

ENT

New Delhi | London | Philadelphia | Panama

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Self Assessment and Review: ENT

Dedicated to

SAI BABA

Just sitting here reflecting on where I am and where I started, I could not have done

it without you Sai Baba I praise you and love you for all that you have given me and thank you for another beautiful day to be able to sing and praise

you and glorify you you are my amazing god

“It can be very difficult to sculpt the idea that you have in mind If your idea doesn’t match the shape of the stone, your idea may have to change because you have to accept what is available in the rock”

Fevereiro 1999 in Arctic Spirit

Dear Students,

I wish to extend my thanks to all of you for your overwhelming response to all the six editions of my book I am extremely delighted by the wonderful response shown by the readers for the 6th edition and proving it again as the bestseller book on the subject Thanks once again for the innumerable e-mails you have sent in appreciation of the book

With the experience, which I have gained working as a faculty and being so closely associated with PG Aspirants, it’s not how much you study which matters rather, its how wisely you study which matters the most.

Since we are not human prodigies (at least I don’t consider myself as one and 90% PG Aspirants are somewhat similar), we cannot remember everything about 19 subjects We need to have a strategic plan to crack AIPG (NEET), which means we have to choose some subjects where we can be sure of not making mistakes

And believe me friends- ENT is one of those subjects, where if you put efforts, it will not let you down With the help of this book, I am just helping you to cake walk through the subject

How to Use This Book

1 Intern and PG Aspirants: The scarcity of time which you have and since you already done ENT in your third year, I would suggest first

read all the New Pattern Questions (Marked as N within the theory) See all diagrams, instruments and previously asked questions with answers Initially do not read the theory, if you are unable to answer the question correctly of some particular topic, then read the theory of that topic from the book Although, I strongly recommend you to go through anatomy of ear, nose, larynx and pharynx along with their tumors from this book

2 Undergraduates and Foreign Graduates: Read the book cover to cover, do not miss out anything, this book will not only lay a strong

foundation for PG Entrance but will also help you in your undergraduate theory and viva exams

Salient Features of 7th Edition

1 Pretext: Detailed yet concise pointwise overview of the topic with many flow charts, tables and mnemonics for better understanding

and retaining

2 New Pattern Questions: To give students an idea of the new questions which could be formed, over 500 new pattern questions have

been added, along side the theory This will help you to reinforce important points from the topic These questions are the potential questions for upcoming exams

3 Instruments and Diagrams: All important instruments related to surgery, diagrams, X-rays, CT scans have been given along with the

topic This is to ensure that students do not miss on any important information and can correlate with them

4 MCQs: All MCQs of AIIMS up to November 2015, PGI up to May 2015, and state-based MCQs up to February 2016 have been included.

5 Authentic Explanations: Explanations from standard and recent edition textbooks have been provided for each answer Different and

controversial MCQs have been explained in details, discussing each option and excluding the incorrect one

I am thankful to Shri Jitendar P Vij (Group Chairman) for allowing me to use illustrations from eminent ENT Textbooks (like Essentials of ENT by Mohan Bansal, TB of ENT by Mohan Bansal and Diseases of ENT by BS Tuli, 2nd Edition) of Jaypee Broth- ers Medical Publishers (P) Ltd, New Delhi, India.

Though at most care has been taken to avoid all possible errors, some minor errors might have crept in, inadvertently I request the readers to kindly point out the same and give their valuable suggestions or feedbacks by e-mail

I wish you all the very best for your upcoming exams and for your bright future.

Preface

Over the years (even if it is 8-10 years), writing acknowledgement for my books, have become an opportunity for self-reflection.

My Family

� Dr Pankaj Hans, my better-half who has always been a mountain of support and who is to a large measure, responsible for what

I am today His calm, consistent approach towards any work, brings some calmness in my hasty, hyperactive, and inconsistent nature

� My Father: Shri H.C Arora, who has overcome all odds with his discipline, hardwork, and perfection.

� My Mother: Smt Sunita Arora, who has always believed in my abilities and supported me in all my ventures – be it authoring a

book or teaching

� My in Laws (Hans family): For happily accepting my maiden surname ‘Arora’ and taking pride in all achievements.

� My Brothers: Mr Bhupesh Arora and Sachit Arora, who encouraged me to write books and have always thought (wrong

although) their sister is a perfectionist

� My Daughter, Shreya Hans (A priceless gift of god): For accepting my books and work as her siblings (Although now she is

showing signs of intense sibling rivalry!!)

My Teachers

� Dr Manju Verma (Prof & Head, Gynae & Obs, MLN MC, Allahabad) and Dr Gauri Ganguli (Prof & Ex-HEAD, Gynae & Obs, MLNMC,

Allahabad) for teaching me to focus on the basic concepts of any subject

My Colleagues: I am grateful to all my seniors, friends and colleagues of past and present for their moral support.

 Dr Manoj Rawal  Dr Pooja Aggrawal  Dr Parul Aggrawal Jain

 Dr Parminder Sehgal  Dr Amit Jain  Dr Sonika Lamba Rawal

Directors of PG Entrance Coaching, who helped me in realizing my potential as an academician.

� Dr Vineet Singh: Director, MIST Coaching

� Mr Sundar Rao: Director, SIMS Academy

My Publishers—Jaypee Brothers Medical Publishers (P) Ltd

� Shri Jitendar P Vij (Group Chairman) for being the best in the industry

� Mr Ankit Vij (Group President) for having constant faith in me and all my endeavours.

� Ms Chetna Malhotra Vohra (Associate Director—Content Strategy) for working hard with the team to achieve the deadlines.

� The entire MCQs team for working laborious hours in designing and typesetting of the book.

Last but not the least

My sincere thanks to all FMGE/UG/PG students, present and past, for their tremendous support, words of appreciation rather

I should say e-mails of encouragement and informing me about the corrections, which have helped me in the betterment

of the book.

Dr Sakshi Arora Hans

delhisakshiarora@gmail.com

Acknowledgements

SECTION I: EAR

1 Anatomy of Ear 3

2 Physiology of Ear and Hearing 32

3 Hearing Loss 40

4 Assessment of Hearing Loss 50

5 Assessment of Vestibular Function 71

6 Diseases of External Ear 82

7 Diseases of Middle Ear 92

8 Meniere’s Disease 124

9 Otosclerosis 132

10 Facial Nerve and its Lesions 141

11 Lesion of Cerebellopontine Angle and Acoustic Neuroma 157

12 Glomus Tumor and Other Tumors of the Ear 164

13 Rehabilitative Methods 170

14 Miscellaneous 177

SECTION II: NOSE AND PARANASAL SINUSES 15 Anatomy and Physiology of Nose 183

16 Diseases of External Nose and Nasal Septum 196

17 Granulomatous Disorders of Nose, Nasal Polyps and Foreign Body in Nose 209

18 Inflammatory Disorders of Nasal Cavity 222

19 Epistaxis 231

20A Diseases of Paranasal Sinus—Sinusitis 241

20B Diseases of Paranasal Sinus—Sinonasal Tumor 260

SECTION III: ORAL CAVITY 21 Oral Cavity 269

SECTION IV: PHARYNX 22 Anatomy of Pharynx, Tonsils and Adenoids 301

23 Head and Neck Space Inflammation and Thornwaldt’s Bursitis 319

24 Lesions of Nasopharynx and Hypopharynx including Tumors of Pharynx 327

25 Pharynx Hot Topics 339

Contents

viii Self Assessment and Review: ENT

SECTION V: LARYNX

26 Anatomy of Larynx, Congenital Lesions of Larynx and Stridor 347

27 Acute and Chronic Inflammation of Larynx, Voice and Speech Disorders 364

28 Vocal Cord Paralysis 380

29 Tumors of Larynx 390

SECTION VI: OPERATIVE PROCEDURE 30 Important Operative Procedures 407

SECTION VII: RECENT PAPERS AIIMS November 2015 421

AIIMS May 2015 423

PGI May 2015 424

PGI November 2014 428

PGI May 2014 431

SECTION VIII: COLOR PLATES

Color Plates iii–xvi

6 Diseases of External Ear

7 Diseases of Middle Ear

12 Glomus Tumor and Other

Tumors of the Ear

13 Rehabilitative Methods

14 Miscellaneous

Ear can be divided into three parts:

I External ear

II Middle ear

III Inner ear (situated in petrous part of temporal bone)

Its lateral surface has characteristic prominences and depressions

(as shown in figure) which are different in every individual even

among identical twins This unique pattern is comparable to

fingerprints and can allow for identification of persons

y The cartilage of pinna is continuous with the cartilage of

external auditory canal

y The cartilage is covered with skin which is closely attached on

lateral surface and slightly loose on medial surface.Q

y The cartilage itself is avascular and derives its supply of

nutrients from the perichondrium covering it

y Clinical importance-stripping of the perichondrium from the

cartilage as occurs following injuries that cause hematoma can

lead to cartilage necrosis and so-called ‘boxers ear’

y Various landmarks on the pinna: see Figure 1.1

– Cymba concha is the area lying between crest of helix

– Another important landmark for mastoid antrum is Mc Ewen’s

triangle or suprameatal triangle Mastoid antrum lies 1 cm

deep to it McEwen’s triangle can be felt under cymba concha

(Discussed later).

– Incisura terminalis: Area between the ascending crus of

the helix and tragus It is devoid of cartilage

Fig 1.1: External features of auricle

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 3

1

Clinical importance: An incision made in this area does not cut

through the cartilage and is used for endaural approach in surgery

y Pinna has 3 extrinsic muscle: 1 Auricularis anterior, 2

Auricularis superior and (3) Auricularis posterior These are all

attached to epicranial aponeurosis and supplied by the facial nerve

y Intrinsic muscles are 6 in number and are small, inconsistent

and without any useful information

y¾ QInnervation of the pinna:

Lateral surface Medial surface

1. Auriculotemporal nerve 1 Lesser occipital nerve—

supplies upper part

2 Greater auricular nerve 2 Most of the medial surface

is supplied by great auricular nerve

3. Auricular branch of vagus

also called as Arnold nerve

3 Auricular branch of vagus

4 Facial nerve (VII) 4 Facial nerve

y Lymphatic Drainage:

– From posterior surface – lymph node at mastoid tip

– Grafts in rhinoplasty: Conchal cartilage is used to

cor-rect depressed nasal bridge

– Graft in tympanoplasty: Tragal and conchal cartilage

and perichondrium are used during tympanoplasty

NEW PATTERN QUESTIONS

Q N1 Part of pinna which lies behind the external audi­

tory meatus is:

a Scaphoid fossa b Concha

c Cymba concha d Tragus

Q N2 Part of pinna lying between ascending crest of helix

and tragus is called as:

a Scaphoid fossa b Concha

c Incisura terminalis d Darwin’s tubercle

Q N3 Major part of the skin of pinna is supplied by:

a Auriculotemporal nerve

b Auricular branch of vagus

c Lesser occipital nerve

d Greater auricular nerve

Q N4 Arnolds nerve is a branch of:

Shape : ‘S’- shaped curve

External Auditory Canal develops from = First brachial cleft/grooveQ

Cartilaginous Part

Forms the outer/lateral 1/3 (8 mm) of external auditory canal

Has a fissure/deficiency - in the anterior part called as Fissures of

SantoriniQ through which parotid or superficial mastoid infection

can appear in the canal and like vice versa

y Skin covering is thick and has ceruminous glands (modified

apocrine sweat glands Q ), pilosebaceous glands and hair.

y Ceruminous and pilosebaceous glands secrete wax (mixture of

cerumen, sebum and desquamated cells is wax)

y Since hair is confined to cartilaginous part – furuncles are seen

only in the outer third of canal.Q

Bony Part

y It forms inner two-thirds (16 mm) Q of external auditory canal

y Skin lining the bony canal is thin and is devoid of hair and

ceruminous glands.Q

y 5 mm lateral to tympanic membrane, bony meatus is narrow

and called Isthmus (Applied – Foreign bodies get lodged in it

and are difficult to remove) Beyond the narrow isthmus, lies a

dilatation called as Anterior meatal recess Any discharge of

middle ear collects in the recess

y Foramen of HuschkeQ is a deficiency present in anteroinferior part of bony canal in children up to 4 years of age, permitting infection to and from the temporomandibular joint

Blood supply: It is also supplied by External carotid artery Lymphatic drainage—follows the auricle

Relationship of external auditory canal - see Flow chart 1.1

Flow chart 1.1: Relations of middle external auditory canal

y QNerve supply:

–¾Anterior wall and roof: Auriculotemporal nerve

–¾Floor and posterior wall: Vagus (arnold nerve))

–¾Posterior wall also receives innervation from: Facial nerve (Importance–Hypoesthesia of the posterior meatal wall is

seen in case of facial nerve injury, known as Hitzelberger’s sign)

NEW PATTERN QUESTIONS

Q N5 Which of the following statement is correct with

respect to EAC of newborn:

a In newborn cartilaginous part of EAC is absent

b In newborn bony part of EAC is absent

c Both bony and cartilaginous part are present

but EAC is short

d Both bony and cartilaginous part are present

and EAC of newborn and adults are of same size

Q N6 All of the following are seen in bony part of EAC

Q N7 The cough response caused while cleaning the ear

canal is mediated by stimulation of:

a The V cranial nerve

b Innervation of external ear canal by C1, C2

c The X cranial nerve

d Branches of the VII cranial nerve

TYMPANIC MEMBRANE (FIG 1.2)

y It is the partition between external acoustic meatus and middle

ear, i.e it lies at medial end of external auditory meatus

y Tympanic membrane is 9–10 mm tall, 8–9 mm wide and

0.1 mm thick and is positioned at angle of 55° to floor

y Area of adult tympanic membrane is 90mm2 of which only

55 mm2 is functional

y It is shiny and pearly grayQ in color

y Normal tympanic membrane is mobile with maximum mobility

being in the peripheral part.Q

Fig 1.2: Tympanic membrane showing attic, malleus handle,

umbo, cone of light and structures of middle

ear seen through it on otoscopy

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 5

y Situated above the lateral process

of malleus between the notch

of Rivinus and the anterior and posterior malleal folds

of Rivinus

¾

y The central part is tented inward at the level of tip of malleus and is called as umbo

¾

y Cone of light is seen radiating from tip of malleus

to the periphery in the anteroinferior quadrant.Q

¾

y Prussak’s space is a shallow

recess within the posterior part of pars flaccida

Note: Negative pressure in middle ear

due to blockage of Eustachian tube leads to formation of retraction pocket and primary choleastatoma in pars flaccida as PF is more flaccid

Layers of Tympanic Membrane

Arterial supply: Vessels are present only in connective tissue layer

of the lamina propria

Arteries supplying tympanic membrane are:

y Medial/inner surface – Tympanic branch of glossopharyngeal nerve (k/a Jacobson’s nerve)

¾

¾ Auriculotemporal nerve (CN V3): It is a branch of mandibular

division of trigeminal nerve and supplies anterior half of lateral surface of TM

¾

¾ CN X (vagus nerve): Its auricular branch (Arnold’s nerve)

supplies to posterior half of lateral surface of TM

¾

¾ CN IX (glossopharyngeal nerve): Its tympanic branch

(Jacobson’s nerve) supplies to medial surface of tympanic

membrane

MIDDLE EAR CLEFT (FIG 1.3)

Ear cleft in the temporal bone, consists of tympanic cavity (middle ear), Eustachian tube and mastoid air cell system

Contd

Contd

y Sometimes the portion of middle ear around the tympanic

orifice of the Eustachian tube is called as protympanum.

Epitympanum Mesotymparum Hypotymparum

¾

y Part which lies above the

level of Pars Tensa

y¾Incudomalleolar joint

y¾Chorda tympani

¾

y Part which lies

at the level of Pars tensa

¾

y Transverse diameter:

2 mm

¾

y Contains:

– M a l l e u s : Handle – Incus long process–¾Whole of stapes

¾

y pedial joint

Incudosta-¾

y Part which lies below the level of Pars tensa

¾

y Transverse diameter:

4 mm

¾

y Contains nothing

Prussak's Space

y Also called superior recess of Tympanic membrane It lies

between neck of malleus (medially) and pars flaccida (laterally

in the epitympanum It is bounded above the fibers of lateral

malleolar fold and below by lateral process of malleus

y Importance of this space: It is most common site o f

cholestea-tom The cholesteatom a may extend to posterior

mesotym-panum infection here does not drain easily and causes attic

pathology

Boundaries of Middle Ear

y Middle ear is like a six sided box with a: roof, floor, medial wall,

lateral wall, anterior wall, posterior wall

Fig 1.4: Parts of middle ear seen on coronal section

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 6

Fig 1.3: Parts of middle ear cleft

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 6

Roof

Is formed by a thin plate of bone called tegmen tympani.Q

y It separates tympanic cavity from the middle cranial fossa. Q

y Tegmen tympani is formed both by petrous and squamous

part of temporal bone and the petrosquamous line (Korners septum) Which does not close until adult life and can provide

a route of access for infection into the extradural space in children

NEW PATTERN QUESTIONS

Q N8 Korner's septum is seen in:

Q N10 Space between pars tensa and anterior malleolar

fold is called as:

a Von Troeltsch anterior pouch

b Facial recess

c Sinus tympani

d Prussak space

Floor or Jugular Wall

It is a thin plate of bone which separates tympanic cavity from the jugular bulb.Q

y In the floor close to the medial wall lies a small opening which allows entry of tympanic branch of glossopharyngeal nerve

(Jacobson nerve) into the middle ear.

Anterior Wall or Carotid Wall (Figs 1.5 and 1.6)

y It is a thin plate of bone which separates the cavity from internal

carotid artery

y From above downwards features seen on anterior wall are

– Canal for tensor tympani (canal containing tensor

tympani muscle which extends to the medial wall to

form a pulley called as processus cochleariformis) The

cochleariformis process, serves a useful landmark and

denotes the location of anterior most part of horizontal

segment of facial nerve

– Opening for Eustachian tube

– Internal carotid artery (carotid canal)

Fig 1.5: Dimensions of tympanum

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd.,

Fig 1.6: Six boundaries of tympanum Medial wall is seen

through the tympanic membrane

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 7

Fig 1.7: Facial recess and sinus tympani relations with facial

nerve and pyramidal eminence

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan Bansal, Jaypee Brothers p 7

– Canal of Huguier for passage of chorda tympani nerve

out of temporal bone anteriorly through the medial end

of petrotympanic fissue to joint the lingual nerve in the infratemporal fossra It carries taste from anterior two-thirds of tongue and secretomotor fibers to submaxillary and sublingual gland

– Glasserian fissure below canal of Huguier transmits

tym-panic artery and anterior ligament of malleus

Point to Remember

Anterior wall of middle ear is close related to internal carotid artery; posterior wall is occupied by facial nerve and floor is mainly venous occupied by internal jugular vein

– Remember anterior wall of middle ear is close related to internal carotid artery; posterior wall is occupied by facial nerve and floor is mainly venous occupied by internal jugular vein

The Posterior Wall

It lies close to the mastoid air cells It has the following main features:

y Aditus–an opening through which attic communicates with

the mastoid antrum

y A bony projection called the pyramid from which originates

stapedius muscle

y Facial nerve runs in the posterior wall just behind the pyramid

Facial recess (Fig 1.7) also called suprapyramidal recess is a

depression in the posterior wall lateral to the pyramid It is bounded

medially by external genu of facial nerve, laterally by chorda

tympani nerve, superiorly by fossa incudis (in which lies the short process of incus) and anterolaterally by tympanic membrane

NOTE

In the intact canal wall mastoidectomy, middle ear is approached (posterior tympanotomy or facial recess approach) through the facial recess without disturbing posterior meatal wall (Fig 1.8)

8 SECTION I Ear

Fig 1.9: Medial wall of middle ear

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 8

Medial Wall

It separates the tympanic cavity from internal ear It is formed by labyrinth The main features on medial wall are (Fig 1.9):

y A bulge called as promontory formed by basal turn of cochlea Q

y Fenestra vestibuli (oval window Q) lies posterosuperior

(behind and above) to the promontory and opens into scala vestibuli It is occupied by foot plate of stapes fixed by annular ligament Its size on average is 3.25 mm long and 1.75 mm wide

y Fenestra cochleae (round window) lies posteroinferior to

the promontory and opens into scala tympani of cochlea It is

closed by secondary tympanic membrane The round window

is closest to ampulla of posterior semicircular canal Round window is a triangular opening

y Prominence of facial nerve canal (k/a Fallopian canal) lies above the fenestra vestibuli curving downward into posterior wall of middle ear

y Anterior to oval window lies a hook-like projection called the

processus cochleariformis Q for tendon of tensor tympani Q

y The cochleariform process marks the level of the genu of the facial nerve which is an important landmark for surgery of the facial nerve

y The round window opening is separated from the oval window

opening by a bony ridge called the subiculum

y The ponticulus – is another bony ridge below oval window.

y Medial to the pyramid is a deep recess called as sinus tympani

(infrapyramidal recess or medial facial recess) which is bounded

below by subiculum and above by ponticulus It is the most inaccessible site in the middle ear and mastoid Its impor­ tance is that cholesteatoma which has extended upto it, is difficult to eradicate.

y Facial recess is superficial to sinus tympani and is separated from it by descending part of facial N

Nerve supply of middle ear

Is by Tympanic Plexus.

y Tympanic plexus is formed by:

– Tympanic branch of IX nerve (Jacobson nerve)– The sympathetic plexus

y They form a plexus on the promontory and provide branches

to the tympanic cavity, Eustachian tube and mastoid antrum and air cells

Blood supply

y Arteries supplying the walls and contents of the tympanic cavity arise from both the internal and external carotid system Arteries involved are:

(i) Anterior tympanic artery, (ii) Inferior tympanic artery, (iii) Stylomastoid artery

Lymphatic drainage Middle ear: Retropharyngeal and Parotid nodes Eustachian tube: Retropharyngeal group

Fig 1.8: Posterior tympanotomy Structures of middle ear seen

through the opening of facial recess

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 7

Fossa Incudis: It is a depression on the posterior wall and contains

the short process of incus

Sinus tympani (Infrapyramidal tympani): This deep recess lies

medial to the pyramid It is bounded by the subiculum below and

ponticulus above (see extra edge)

NEW PATTERN QUESTION

Q N11 The site exit of chorda tympani from middle ear

Fig 1.10: Middle ear ossicles

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 8

AUDITORY OSSICLES (FIG 1.10)

y These are malleus, incus and stapes (MIS)

y It comprises of head, neck, anterior process, lateral process,

manubrium and umbo

y Ossicles ossify by fourth month of intrauterine life (first bones in the body to do so).

Joints of the Ossicles

a The incudomalleolar joint – Saddle joint

b Incudostapedial joint – Ball and socket jointBoth of them are synovial joints

Function of Ossicle

y Ossicles conduct sound energy from the tympanic membrane

to oval window and then to inner ear fluid

Muscles of Tympanic Cavity: Tympanic Cavity has Two Muscles

Tensor tympani develops from 1st arch Origin: Cartilaginous pharyngo tympanic tube, greater wing

of sphenoid, its own bony canal

Insertion: Upper part of handle of malleus Nerve supply: Mandibular nerve (anterior or motor branch) Function: Contraction pulls handle of malleus medially, tensing

tympanic membrane to reduce the force of vibrations in response

to loud noise

Stapedius develops from 2nd Arch

Origin: Attached to inside of pyramidal eminence Insertion: Neck of stapes

Innervation: Branch of facial nerve

Function: Contraction usually in response to loud noises, pulls

the stapes posteriorly and prevents excessive osscillation

MASTOID ANTRUM Mastoid bone is a cancellous or spongy bone

y It hs numerous air cells The largest of which is mastoid antrum.

Types Sclerotic (20%)

y It is an air sinus in the petrous temporal bone

y Its upper anterior wall has the opening of aditus, while medial wall is related to posterior semicircular canal (SCC)

y Posteriorly lies the sigmoid sinus

y The posterior belly of digastric muscle forms a groove in the base of mastoid bone The corresponding ridge inside the mastoid lies lateral not only to sigmoid sinus but also to facial nerve and is a useful landmark

y The roof is formed by tegmen antri separating it from middle cranial fossa and temporal lobe of brain.Q

y Anteroinferior is the descending part of facial nerve canal

(or Fallopian canal).

y Lateral wall is formed by squamous temporal bone and is easily palpable behind the pinna

10 SECTION I Ear

y Mastoid develops from squamous and petrous part bone of

temporal between which lies petrosquamous suture which

usually disappears

The mastoid antrum but not the air cells are well developed at

birth Pneumatization begins in the first year and is complete by

4 to 6 years of age

Korner's septum: Korner's septum is persistence of

petro-squamous suture in the form of a bony plate which separates

superficial squamous cells from the deep petrosal cells Korner's

septum is surgically important as it may cause difficulty in

locating the antrum and the deeper cells, and thus lead to

incomplete removal of disease at mastoidectomy Mastoid

antrum cannot be reached unless the Korner's septum has been

removed

Landmark for Mastoid Antrun

MacEwen’s Triangle (Fig 1.11)

It is bounded by:

y Above by temporal line

y Anteroinferiorly by posterosuperior segment of bony

external auditory canal

y Posteriorly by a line drawn as a tangent to the external canal

Fig 1.11: a Supramastoid crest or temporal line, b Posterosuperior

segment of EAC, c Tangent drawn to external canal

NOTE

Anterior to Macewen's triangle on the mastoid bone, a projection

can be seen This is called spine of henle It is also an important

landmark for mastoid antrum

Extra Edge:

Master Antrum: In an adult, it lies 12–15 mm deep to suprameatal

triangle But at the time of birth, it just lies 2 mm deep to

suprameatal triangle The thickness of the bone increase upto

puberty at the rate of 1 mm per year

NEW PATTERN QUESTION

Q N12 Which of the following is not a pneumatic bone:

c Maxillary d Mastoid

EUSTACHIAN TUBE

It is a channel connecting the tympanic cavity with the nasopharynx

(Fig 1.12) It is also called pharyngotympanic tube It is lined by

Ciliated columnar epithelium

y It helps to equalize pressure on both sides of tympanic membrane

y Length of Eustachian tube is 36 mm (reached by the age of

7 years)

y Lateral third (i.e 12 mm) is bony

y Medial 2/3 (i.e 24 mm) is fibrocartilaginous

y In adults it is placed at an angle of 45° with saggital plane,

while in infants it is short (length 13-18 mm), wide and placed horizontally

So in infants infections of middle ear are more common

y Muscles of Eustachian tube are tensor palati Q (dilator tube

is a part of it) supplied by branch of mandibular nerve Q and

levator palatiQ supplied by pharyngeal plexus through XIth cranial nerve.Q

y Arterial supply is through branches from ascending pharyngeal artery, middle meningeal artery and artery of pterygoid canal

(both branches of maxillary artery).

y Venous drainage is to the pterygoid venous plexus

y Nerve supply is by tympanic plexus

Fig 1.12: Right Eustachian tube INNER EAR (Also called labyrinth)

y It consists of a bony labyrinth (contained within the petrous temporal bone) along with the membranous labyrinth

y It serves the most important function of hearing and equilibrium

y The inner ear is connected to posterior cranial fossa by an opening in petrous temporal bone called as internal acoustic meatus

y Parts: A Bony labyrinth, B Membranous labyrinth

BONY LABYRINTH (FIG 1.13)

y It lies in the temporal bone

y It consists of vestibule, the semicircular canals and the cochlea

which are filled with perilymph Q , which resembles CSF but is rich

in Na+ and poor in K+.

y Fallopius in 1561 described cochlea and labyrinth.

recess �¾Elliptical recess �¾Opening of aqueduct of vestibule

For the saccule For the utricle Carries endolymphatic

duct

y In the lateral wall lies the oval window (Fenestra vestibule)

Semicircular Canals (SCC)

They are three in number, the lateral, posterior and superior and

lie at right angles (90°) to each other The area of bony labyrinth

which lies in between 3 SCC is called solid angle.Q

y Ampulla: One end of each canal dilates to form the ampulla,

which contains the vestibular sensory epithelium and opens

independantly in vestibule Ideally there should be 6 openings

of 3 SCC but the non ampullated ends of posterior and superior

SCC fuse together to form a common crus called as 'crus

commune' (4 mm length) which then opens into the vestibule,

So the 3 semicircular canals open in vestibule by “5” openings

Cochlea (Bony Cochlea)

y Has approximately two- and- one half turns.Q

y Coils turn about a central bone called modiolus Q

y The cochlear tube is 30 mm long

y Cochlea converts mechanical soundwaves to electrical signal

which can be transmitted to brain This function is primarily

performed by cochlea hair cells

y The modiolus houses spiral ganglion cells destined to innervate

cochlea hair cells, in an area called as Rosenthal canal.

y Arising from the modiolus is a thin shelf of bone which spirals

upward within the lumen of the cochlea as the bony spiral

lamina.

– Spira lamina divides the cochlear canal into upper scala

vestibuli and lower scale tympani The scala vestibuli

and tympani scala are continous with each other through

helicotrema at the apex of cochlea (Fig 1.14)

Fig 1.13: Bony labyrinth of left side

External features seen from lateral side

– Scala vestibuli is closed by the footplate of stapes, which separates it from the air-filled middle ear

– The scala tympani is closed by secondary tympanic brane

mem-– Aqueduct of cochlea connects the scala tympani with

the subarachnoid space

– Spiral lamina gives attachment to the basilar membrane

Point to Remember

¾

¾ The bony labyrinth (bony cochlea) has 3 openings

¾ – The oval window (fenestra vestibule) present in scala

vestibule and closed by foot plate of stapes

¾ – Round window (fenestra cochleae) present in scala

tympani and covered by secondary tympanic membrane

¾ – Cochlear canaliculus which transmits a small ven to

inferior petrosal sinus

¾

¾ The bony labyrinth communicates with subarachnoid space via cochlear aqueduct Thus infection of labyrinth can lead

to meningitis and viceversa

MEMBRANOUS LABYRINTH (FIG 1.15)

y It lies within the osseus/bony labyrinth and is filled with endolymphatic fluid.Q

y It is separated from the bony labyrinth by perilymphatic fluid.Q

y It consists of cochlear duct, utricle, saccule, semicircular ducts, endolymphatic duct and sac

Fig 1.14: Cochlea: Peri- and endolymphatic systems relations

with cerebrospinal fluid (CSF)

Courtesy: Textbook of Diseasses of Ear, Nose and Throat, Mohan Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 14

12 SECTION I Ear

The basal coil of cochlea responds to higher frequency sounds whereas the apical turns respond to low frequency sounds

NEW PATTERN QUESTIONS

Q N13 Not included in bony labyrinth:

a Cochlea

b Semicircular canal

c Organ of corti

d Vestibule

Q N14 The bony cochlea is a coiled tube making turns

around a bony pyramid called:

Utricle and Saccule

y The utricle lies in the posterior part of bony vestibule

y It receives the five openings of the three semicircular ducts

y It is connected to the saccule through utriculosaccular ducts.Q

y The sensory epithelium of the utricle is called the macula

and is concerned with linear accelerationQ and deceleration.Q

y The saccule also lies in the bony vestibule.

y Its sensory epithelium is also called the macula Q Its exact

function is not known It probably also responds to linear

accelerationQ and deceleration.Q

Endolymphatic Duct and Sac

Endolymphatic duct is formed by the union of two ducts, one

each from the saccule and the utricle.Q i.e utriculo saccular ducts

Its terminal part is dilated to form endolymphatic sac which lies

under the dura on the posterior surface of the petrous bone Thus

endolymphatic duct connects utriculosaccular duct to brain The

endolymphatic sac is responsible for absorption of endolymph

(fluid which fills whole of membranous labyrinth)

Donaldson's line: This line is a surgical landmark for

endolymphatic sac It passes through horizontal bisecting the

posterior semicircular canal The endolymphatic sac that appears

as thickening of the posterior cranial fossa dura is situated inferior

to Donaldson's line

Cochlear Duct (Membranous Cochlea)

y Also called membranous cochlea Q or the scala media Q It is a

blind coiled tube, Which takes 21/2–23/4 turns around a bony

axis called 'modulus'.

y It appears triangular on cross section and has three walls

formed by

– The basilar membrane, which supports the organ of cortiQ

– The Reissner’s memebrane which separates it from the

scala vestibuliQ (Fig 1.16)

– The stria vascularis, which contains vascular epithelium and

is concerned with secretion of endolymph.Q

y Cochlear duct is connected to the saccule by ductus reunions.Q

Fig 1.15: Membranous labyrinth of left side: External features

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 15

Fig 1.16: Structure of cochlear canal after its cut section

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 15

Q N18 The bony labyrinth has following except:

Inner Ear Fluids and their Circulation

y There are two main fluids in the inner ear, perilymph and

endolymph

y Perilymph resembles extracellular fluid and is rich in Na ionsQ

It fills the space between the bonyQ and the memebranous

labyrinth Q It communicates with CSF through the aqueduct

of cochleaQ which opens into the scala tympani near the round

window

y Endolymph fills the entire membranous labyrinthQ and

resembles intracellular fluidQ, being rich in K ionsQ It is secreted

by the secretory cells of the stria vascularisQ of the cochlea and

by the dark cells (present in the utricle and near the ampullated

ends of semicircular ducts)

Blood Supply of Labyrinth

y Blood supply of labyrinth is through labyrinthine arteryQ

which is a branch of anteroinferior cerebellar arteryQ but may

sometimes arise from basilar artery

y It divides in the labyrinth – as

Venous Drainage

y It is through three veins namely internal auditory, vein of cochlear

aqueduct and vein of vestibular aqueduct which ultimately drain

into inferior petrosal sinus and lateral venous sinus

NOTE

¾

y Blood supply to the inner ear is independant of blood supply

to middle ear and bony otic capsule, and there is no cross circulation between the two

¾

y Blood supply to cochlea and vestibular labyrinth is segmental, therefore, independent ischemic damage can occur to these organs causing either cochlear or vestibular symptoms

Internal Acoustic Meatus

y Internal acoustic meatus is 1 cm long and has a vertical length

– Fundus (applied to labyrinth)

Fig 1.17: Fundus of Internal acoustic meatus

y Bills bar is a vertical crest of bone, which divides superir

compartment of canal into anterior compartment for facial N and posterior compartment for superior vestibular N

y It is divided into superior and inferior compartment by Falciform (Transverse) crest

y Structures which pass through internal acoustic meatus to cranium and vice versa

St Francis College of India

St = Superior vestibular N

Francis = Facial N College = Cochlear N

of

India = Inferior vestibular NMnemonic

Sensory end Organs of Balance

The sensory organs or balance are:

Cristae:

y Present in semicircular canal

y Responsible for sensing rotational and angular movements

Maculae:

y Present in utricle and saccule

y Responsible for sensing linear acceleration, head tilt and gravity

14 SECTION I Ear

DEVELOPEMENT OF EAR

Pinna

y In the sixth week of embryonic life, six tubercles (Hillocks of

His) (Fig 1.18) appear around the first and second branchial

arch They progressively grow and coalesce and form the auricle

y Tragus develops from the first branchial arch The remaining

pinna develops from second arch

y By the 20th week, pinna attains adult shape

Fig 1.18: Development of pinna (A) from six hillocks of His (B)

around the firstbranchial cleft (1 from firstand 2–6 from

second branchial arch)

Courtesy: Textbook of Diseases of Ear, Nose and Throat, Mohan

Bansal, Jaypee Brothers Medical Publishers Pvt Ltd., p 19

Point to Remember

Applied Anatomy:

¾

¾ Preauricular sinus: Results due to defective fusion

between 1st and 2nd arch, hence it is situated between

tragus and rest of pinna

Opening of the sinus is found in front of the ascending limb

of the helix

¾

¾ Anotia is complete absence of pinna and usually forms a

part of the first arch syndrome

¾

¾ Microtia: It is developmental anomaly where size of pinna

is small

¾

¾ The surgical reconstruction of pinna is done after 6 years

of age using costal cartilage This is because pinna attains

adult size by that time

NEW PATTERN QUESTIONS

Q N20 Pinna attains adult size by:

a 6 hours after birth

b 8–9 years after birth

c 6–8 months after birth

d 2–4 years after birth

Q N21 A new born presents with bilateral microtia and

external auditory canal atresia Corrective surgery

is usually performed at:

a < 1 year of age b 5–7 years of age

External Auditory Canal

y External auditory canal (EAC) develops from the first branchial cleft

y At birth external canal is cartilaginous, the bony part develops later

y At the time of birth, the tympanic membrane is nearly horizontal in orientation Tympanic membrane becomes more vertical (50–60 from horizontal) during 3rd year of life

Point to Remember Applied Anatomy:

Atresia of canal: The recanalization of meatal plug, which

begins from the deeper part near the tympanic membrane and progresses outwards, forms the epithelial lining of the bony meatus This is the reason why deeper meatus is sometimes developed while there is atresia of canal in the outer part

Tympanic Membrane

It develops from all the three germinal layers:

y Ectoderm: Outer epithelial layer is formed by the ectoderm

y Mesoderm: The middle fibrous layer develops from the

mesoderm

y Endoderm: Inner mucosal layer is formed by the endoderm

NEW PATTERN QUESTIONS

Q N22 External auditory canal is formed by:

a 1st branchial groove

b 1st visceral pouch

c 2nd branchial groove

d 2nd visceral pouch

Q N23 Call Aural fistula is:

a 1st branchial cleft anomaly

b 2nd branchial cleft anomaly

c 1st branchial pouch anomaly

d 2nd branchial pouch anomaly

Middle Ear

y Endoderm of Tubotympanic Recess: The eustachian tube,

tympanic cavity, attic, antrum and mastoid air cells are derived from the endoderm of tubotympanic recess which arises from the first and partly from the second pharyngeal pouches

y First Branchial Arch: Malleus and incus develops from

mesoderm of the first arch

y Second Branchial Arch: The stapes suprastructures (i.e head,

neck and the 2 crura) develops from the second arch Whereas the stapes footplate and annular ligament are derived from the otic capsule

y The ossicles attain their adult configuration by 20 weeks

Inner Ear

y Development of the inner ear, which begins in third week of fetal life, is complete by the 16th week

y Auditory Placode: The auditory placode, which is thickened

ectoderm of hind brain, gets invaginated and forms auditory vesicle (otocyst)

y Auditory Vesicle: The auditory vesicle differentiates into

endolymphatic duct and sac, utricle, semicircular ducts,

saccule and cochlea i.e membranous labyrinth develops

from ectoderm.

y Development of pars superior (semicircular canals and utricle)

takes place earlier than pars inferior (saccule and cochlea) The

pars superior is phylogenetically older part of labyrinth

y Bony labyrinth develops from mesoderm.

y The cochlea develops by 20 weeks of gestation and the fetus

can hear in the womb of the mother The great Indian epic

of Mahabharata, which was written thousands of years ago,

mentions that Abhimanyu son of great warrior Arjun while in

his mother’s womb heard conversation (regarding the art of

battle ground) of his mother and father

Points to Remember

Applied Anatomy

Dysplasias of Inner Ear (Dhingra 6/e, p 115)

¾

¾ Mondini dysplasia: The cochlea takes only 1.5 turns instead

of 21/4 to 23/4 turns Cochlear implants are useful in this condition

¾

¾ Scheibe dysplacia: M/C inner ear malformation The bony

labyrinth is normal Involves dysplasia of cochlea and saccule

(hence also called cochleosaccular dysplasia) Inherited as

Autosomal Recessive trait

¾

¾ Alexandar dysplasia: Affects the basal turn of cochlea

Thus high frequencies are only affected Hearing aids are

beneficial in this condition

Contd

Contd

¾

¾ Michel aplasia: Complete absence of bony and

mem-branous labyrinth These patients are not benefited with either hearing and or cochlear implant

¾ – MalleusQ

¾ – IncusQ

¾ – StapesQ

¾ – LabyrinthQ

¾ – CochleaQ

y Vertical and anteroposterior dimensions of middle ear are 15 mm each while transverse dimension is 2 mm at mesotympanum, 6 mm above at the epitympanum and 4 mm below in the hypotympanum Thus, middle ear is the narrowest between the umbo and promontory

y Boundaries of facial recess are facial nerve medially, chorda

tympanic (laterally) and fossa incudis (above)

y Eddy currentsQ in the external auditory meatus do not allow water to reach TM while swimming

y Organ of corti is filled with cortilymph

y The electrodes in cochlear implant are placed in the scala tympani via round window

16 SECTION I Ear

EXPLANATIONS AND REFERENCES TO NEW PATTERN QUESTIONS

N1 Ans is b i.e Concha

For this, refer to Fig 1.1—Concha is the part which is lying behind the external auditory meatus

N2 Ans is c i.e Incisura terminalis

For this, refer to Fig 1.1—The part of pima lying between ascending crest of helix and tragus is incisura terminalis

Major part of pinna is supplied by greater auricular nerve (C2, 3)

Auricular branch of vagus (CNX) is called as arnold nerve

N5 Ans is b i.e In newborn, bony part of EAC is absent Ref Tuli 2/e, p 6

In newborns, bony part of EAC is absent cartilaginous part is present and EAC is short 20 mm

Fissures of santorini are seen in cartilaginous part of external auditory canal and not bony part Rest all are seen in bony part

“Irritation of the auricular branches of the vagus in the external ear (by ear wax, syringe, etc.) may reflexly cause cough, vomiting, or even death due to sudden cardiac inhibition.”

Auricular branch of the vagus nerve is also known as Arnold’s nerve or Alderman’s nerve.

Also Know

Similarly irritation of recurrent laryngeal nerve by enlarged lymph nodes in children may also produce a persistent cough

The petrosquamous suture may persist as a bony plate - the Korners septum

N9 Ans is d i.e Prussak space

Prussak’s space: It is bounded by pars flaccida (laterally), neck of malleus (medially), lateral process of malleus (inferiorly), and lateral malleal

ligament (superiorly) Posteriorly, it opens into epitympanum

N10 Ans is a i.e Von Troeltsch anterior pouch

Von Troeltsch anterior pouch: It is situated between the pars tensa and anterior malleolar fold.

See the text for explanation

Mastoid is a spongy bone Maxilla, frontal, sphenoid and ethmoid

Organ of corti is a part of membranous labyrinth, not bony labyrinth.

"The bony cochlea is a called tube making 2.5 to 2.75 turns around a central pyramid of bone called modulus"

N15 Ans is a i.e Organ of corti Ref Dhingra 6/e, p 13

"Organ of corti is the sense organ of hearing and is situated on the basilar membrane"

The electrodes of cochlear implant are placed into the scala tympani by passing through round window

Donaldson line—Details given in text

Also Know:

¾

y Citelli's angle (sinodural angle): It lies between the sigmoid sinus and middle fossa dura mater.

¾

y Bill's island: This thin plate of bone left on sigmoid sinus during mastoidectomy helps in retracting the sigmoid sinus It should not

be confused with Bill's bar, which lies in the fundus of internal auditory canal

¾

y Solid angle: This area of bony labyrinth lies between the three semicircular canals.

¾

y Trautmann's triangle: This area is bounded by the bony labyrinth anteriorly, sigmoid sinus posteriorly and the superior petrol

sinus superiorly Any infection in the posterior canal fossa can spread through this triangle and can be approached by removing

the bone in between the triangle

Endolymphatic sac is present in the membranous labyrinth and not bony labyrinth

Read the text for explanation

N19 Ans is c i.e Both

As discussed in the text—cochlear aqueduct connects bony labyrinth to subarachnoid space Internal acoustic meatus lies in petrous part of temporal bone, also connects inner ear to cranium

N20 Ans is b i.e 8–9 years after birth

Tympanic membrane attains adult size by 8-9 years of age

N21 Ans is b i.e 5­7 years of age

Read the preceeding text for explanation

External auditory canal develops from the first branchial cleft

Collaural fistula: This is an abnormality of the first branchial cleft The fistula has two openings: one situated in the neck just below and behind

the angle of mandible and the other in the external canal The track of the fistula passes through the parotid in close relation to the facial nerve Treatment is excision of the tract

18 SECTION I Ear

1 Ceruminous glands present in the ear are:

[AIIMS May 05]

a Modified eccrine glands b Modified apocrine glands

c Mucous gland d Modified holocrine glands

2 Nerve supply for external ear are all except: [MAHE 07]

a Greater occipital nerve b Greater auticular nerver

c Auriculotemporal nerve d Lesser occipital nerve

3 All of the following nerves supply auricle and extrernal

a Trigeminal nerve b Glossopharyngeal nerve

c Facial nerve d Vagus nerve

4 Which of the following nerves has no sensory supply to

a Lesser occipital nerve

b Greater auricular nerve

c Auricular branch of vagus nerve

d Tympanic branch of glossopharyngeal nerve

5 Sensory supply of external auditory meatus is by:

a Pterygomandibular ganglion [PGI June 07]

b Geniculate ganglion

c Facial nerve

d Auriculotemporal nerve

6 Skin over pinna is fixed: [JIPMER 95]

a Firmly on both sides b Loosely on medial side

c Loosely on lateral side d Loosely on both side

7 Dehiscence of anterior wall of the external auditory canal

cause infection in the parotid gland via

a Fissure of Santorini b Notch of ramus

c Petrous fissure d Retropharyngeal fissure

8 What is the color of the normal tympanic membrane?

9 The most mobile part of the tympanic membrane:

10 Pars flaccida of the tympanic membrance is also called:

b Shrapnell’s membrane

c Basilar membrane

d Secondary tympanic membrane

11 Anterior wall of tympanic cavity contains: [PGI May 11]

b Bony part of pharyngotympanic tube

c Processus cochleariformis

d Pyramid

e Tensor tympani muscle

12 The distance between tympanic membrane and medial

wall of middle ear at the level of center is: [PGI 00]

19 In otoscopy, the most reliable sign is: [AIIMS 92]

a Lateral process of malleus

b Handle of malleus

c Umbo

d Cone of light

20 Nerve supply of the tympanic membrane is by: [AI 95]

a Auriculotemporal b Lesser occipital

c Greater occipital d Parasympathetic ganglion

21 Nerve supply of tympanic memberane: [PGI Dec 02]

a Auriculotemporal b Auricular branch of vagus

c Occipital NV d Great auricular NV

e Glossopharyngeal NV

22 Which of the following is false about tympanic mem­

a Cone of light is anteroinferior

b Shrapnell’s membrane is also known as pars flaccida

c Healed perforation has three layers

d Anterior malleolar fold is longer than posterior

23 Sensory nerve supply of middle ear cavity is provided

c TM joint d Vestibule of nose

26 Stapedius is supplied by: [JIPMER 92]

a Maxillary nerve b Facial nerve

c Auditory nerve d Mandibular disese

QUESTIONS

27 Regarding stapedial reflex, which of the following is

a It helps to enhance the sound conduction in middle ear

b It is a protective reflex against loud sounds

c It helps in masking the sound waves

d It is unilateral reflex

28 Tensor tympani is supplied by: [Jipmer 2002]

a Anterior part of V nerve

b Posterior part of V nerve

c IX nerve

d VII nerve

29 Nerve of the pterygoid canal is also known as: [PGI]

a Arnold’s nerve b Vidian nerve

c Nerve of Kuntz d Criminal nerve of Grassi

30 All are components of epitympanum except: [AI 02]

a Body of incus b Head of malleus

c Chorda tympani d Footplate of stapes

31 Prussak’s space is situated in: [MAHE 02]

c Hypotympanum d Ear canal

32 Tegmen seperates middle ear from the middle cranial

fossa containing temporal lobe of brain by: [Karn 06]

a Medical wall of middle ear

b Lateral wall of middle ear

c Roof of middle ear

d Anterior wall of middle ear

33 Facial recess or the posterior sinus is bounded by:

a Medially by the vertical part of VII nerve [TN 2003]

b Laterally by the chorda tympani

c Above by the fossa includ is

d All of the above

34 While doing posterior tympanotomy through the facial

recess there are chances of injury to the following ex­

d Vertical descending part of facial nerve

35 All are true about facial recess except: [JIPMER 2006]

a Supra pyramical recess

b Medially it is bounded by chorda tympani and laterally

by facial nerve

c Important in cochlear implant

d Middle ear can be approached through it

36 Floor of middle ear cavity is in relation with: [AI 2001]

a Internal carotid artery

b Bulb of the internal jugular vein

c Sigmoid sinus

d Round window

37 Promontory seen in the middle ear is: [PGI June 98]

a Jugular bulge b Basal turn of cochlea

c Semicircular canal d Head of incus

38 Process cochleariformis attaches to: [JIPMER 95]

a Tendon of tensor tympani

b Basal turns of helix

c Handle of malleus

d Incus

39 Mac Ewan’s triangle is the landmark for: [MP98]

a Maxillary sinus b Mastoid antrum

c Frontal sinus d None

40 The suprameatal triangle overlies: [JIPMER 91]

a Mastoid antrum b Mastoid air cells

41 Anatomical landmark indicating position of mastoid

42 All of the following form the boundary of MacEwen’s

a Temporal line

b Posterosuperior segment of bony external auditory canal

c Promontory

d Tangent drawn to the external auditory meatus

43 What is the type of joint between the ossicles of ear?

[AI 08]

a Fibrous joint b Primary cartilaginous

c Secondary cartilaginous d Synovial joint

44 Eustachian tube opens into middle ear cavity at:

[UP 2000]

a Anterior wall b Medial wall

c Lateral wall d Posterior wall

45 The length of Eustachian tube is: [AP99; TN 06]

e Opens during swallowing

47 True about Eustachian tube is/are: [PGI June 01]

a Size is 3.75 cm

b Cartilagenous 1/3 and 2/3rd bony

c Opens during swallowing

d Nasopharyngeal opening is narrowest

e Tensor palati helps to open it

48 Which of the following causes opening of Eustachian

a Salpingophayngeus

b Levator veli palatine

c Tensor veli palatini

d None of the abvoe

49 True about Eustachian tube: [PGI Nov 10]

a Length is 36 mm in adults and 1.6 to 3 mm in children

b Higher elastin content in adults

c Ventilatory function of ear better developed in infants

d More horizontal in adults

e Angulated in infants

d Petrous part of squamous bone

51 Inner ear bony labyrinth is: [Karn 06]

a Strongest bone in the body

b Cancellous bone

c Cartilaginous bone

d Membranous bone

a Connects internal ear with subarachnoid space

b Connects cochlea with vestibule

c Contains endoylymph

d Same as S media

53 Infection of CNS spread in inner ear through:

[AIIMS May 10, May 11]

a Cochlear aqueduct b Endolymphatic sac

c Vestibular aqueduc d Hyrtl fissure

54 Which of the following is not a route of spread of infec­

a Directly through openings such as round window and

56 Stapes footplate covers: [AIIMS May 03]

a Round window b Oval window

c Inferior sinus tympani d Pyramid

57 Organ of corti is situated in: [Kerala 98]

a Scala media b Sinus tympani

c Sinus vestibuli d Saccule

58 Movement of stapes causes vibration in: [DNB 02]

a Scala media b Scala tympani

c Scala vestibuli d Semicircular canal

59 Lateral wall of middle ear formed by: [FMGE 13]

d Long bone with Haversian system

62 Labyrinthine artery is a branch of: [AIIMS 91]

a Internal carotid artery

b Basilar artery

c Posterior cerebellar artery

d Anteroinferior cerebellar artery

63 Endolymphatic duct connects which structure:

a Scala media to subdural space [Delhi 05]

b Scala vestibule to aqueduct of cochlea

c Scala tympani to aqueduct of cochlea

d Scala tympani to subdural space

64 Site where endolymph is seen: [Kerala 97]

a Scala vestibuli b Scala media

c Helicotrema d Organ of corti

65 Endolymph in inner ear: [AIIMS May 10]

a Is a filtrate of blood serum

b Is secreted by striae vascularis

c Is secreted by basilar membrane

d Is secreted by hair cells

66 The function of stria vascularis is: [AI 2002]

a To produce perilymph

b To absorb perilymph

c To maintain electric milieu of endolymph

d To maintain electric milieu of perilymph

a 1st pharyngeal arch

b 1st and 3rd pharyngeal arch

c 1st and 2nd pharyngeal arch

d 2nd pharyngeal arch

68 The following structure represents all the 3 components

a Tympanic membrane b Retina

c Meninges d None of the above

69 Vertical crest at the internal auditory canal is:

[AIIMS May 11]

70 Eustachian tube develops from: [PGI 97]

a 2nd and 3rd pharyngeal pouch

b 1st pharyngeal pouch

c 2nd pharyngeal pouch

d 3rd pharyngeal pouch

71 All of the follwoing are of the size of adult at birth expect?

a Tympanic membrane b Ossicle [APPG 06]

c Tympanic cavity d Mastoid

72 Which of the following attain adult size before birth:

[AIIMS Nov 2010]

a Ear ossicles b Maxilla

73 True regarding “Preauricular sinus” is: [MAHE 07]

a Improper fusion of auricular tubercles

b Persistent opening of first branchial arch

c Autosomal recessive pattern

75 True regarding development of the ear: [PGI 2007]

a Eustachian tube develops from 1st cleft

b Eustachian tube opens behind the level of inferior

tur-binate

c Pinna develops from 1st pouch

d Growth of organ of Corti is completed by 5th month

e Ossicles are adult size at birth

76 Foetus starts hearing by what time in intrauterine life:

77 The commonest genetic defect of inner ear causing deaf­

a Michel aplasia

b Mondini aplasia

c Scheibe aplasia

d Alexander aplasia

78 What are the boundaries of Trauttmann’s triangle:

a Bony labyrinth anteriorly [PGI Nov 2012]

b Bony labyringh posteriorly

c Sigmoid sinus posteriorly

d Sigmoid sinus anteriorly

e Superior petrosal sinus superiorly

79 Not correctly matched pair is: [TN 2007]

a Utricle and sacule –Semiciruclar canal

b Oval window –Footplate of staps

c Aditus ad antrum –MacEwen’s triangle

d Scala vestibule –Reissner’s membrane

22 SECTION I Ear

1 Ans is b i.e Modified apocrine glands Ref IB Singh Histology 6/e, p 214-215

Sweat glands are of 2 types:

Eccrine / typical sweat glands Apocrine / Atypical sweat glands

y They open into the hair follicle

y Located on: Axilla, Mons pubis, Circumanal area, Areola, Nipple Ceruminous glands of external acoustic meatus and ciliary glands of eyelids are modified apocrine glands.

2 Ans is a i.e Greater occipital nerve Ref Dhingra 5/e, p 5; 6/e, p 4 Scott Brown 7/e, Vol III p 3106–3107

3 Ans is b i.e Glossopharyngeal nerve

4 Ans d i.e Tympanic branch of glossopharyngeal nerve

5 Ans is d i.e Auriculotemporal nerve Ref Dhingra 6/e, p 4; 5/e, p 5; BDC 4/e, Vol III p 254

Nerve Supply of Ear

External ear

Auricle/pinna External acoustic meatus Tympanic membrane Middle ear Cavity Muscles

Lateral surface y Anterior wall

and roof by auriculotemporal nerve

Lateral surface Tympanic plexus formed by: Tensor tympani by

1 Anteroinferior part by auriculo temporal nerve

receives innervations

by facial nerve through auricular branch of vagus

2 Posteriosuperior part by auricular branch of vagus nerve

2 Superior and inferior Carotympanic nerves (Sympathetic plexus around internal carotid)

Medial surface Medial surface

NOTE

Auriculotemporal nerve is a branch of mandibular nerve (branch of trigeminal nerve)

Remember: Pinna is supplied mainly by 4 nerves:

Greater auricular N

Lesser occipital nerve

Auricular br of Vagus (Arnold N)

Auriculotemporal N

¾

y The Glossopharyngeal nerve does not supply external ear and external acoustic meatus It gives sensory supply to middle ear

EXPLANATIONS AND REFERENCES

6 Ans is b i.e Loosely on medial side Ref Dhingra 6/e, p 2, 5/e, p3

Skin over the pinna is closely adherent to the perichondrium on the lateral surface while it is loosely attached on the medial surface

¾

y The cartilaginous part of external auditory canal—the “fissures of santorini” through which infections can pass from external

ear to parotid and vice versa

¾

y The deficiency present in bony part is “Foramen of Huschke” seen in children up to the age of 4 Through this infections of ear can also pass to parotid gland

8 Ans is a i.e Pearly white Ref Dhingra 5/e, p 61; Maqbool 11/e, p 33; Turner 10/e, p 240

Such a simple appearing question can also confuse us with its options Most of the texts say that tympanic membrane is pearly grey in color

“Normal tympanic membrane is shiny and pearly grey in color.” Dhingra 6/e p55; 5/e, p 61

“Tympanic membrane appears as a greyish white translucent membrane.” Maqbool 11/e, p 33 “In health, the drum head presents a highly gray surface.” Turner 10/e, p 240

So, neither option “a” i.e pearly white nor option “b” i.e grey is fully correct but from ages the answer is taken as pearly white, so

I am in also taking option “a” i.e pearly white as the correct option.

“Movements of tympanic membrane are more at the periphery than at the center where malleus handle is attached.”

Pars flaccida /Shrapnell’s membrane

Situated above the lateral process of malleus between the notch of Rivinus and the anterior and posterior malleal folds

Also know

y Reissner’s membrane – Separates scala media from scala vestibuli in the inner ear (Dhingra 6/e p10, 5/e, p12)

y Basilar membrane – Seen in scala media and supports the organ of Corti (Dhingra 6/e, p10, 5/e p12)

y Secondary tympanic membrane – Closes the scala tympani at the site of round window (Dhingra 5/e, p11)

The anterior wall has a thin plate of bone which separates the cavity from internal carotid It also has two openings; the lower one for Eustachian tube and the upper one for the canal of tensor tympani muscle

The distances separating them are:  Near the roof 6 mm → Epitympanum (Attic)

(between promontary and umbo)

15 Ans is d i.e 90 mm 2 Ref Maqbool 11/e, p 19; Dhingra 6/e, p 446; point 8, 5/e, p 457; point 8

Handle of malleus is 1.3 times longer than process of the incus which constitutes for the lever-action

Area Ratio: The area ratio of tympanic membrane is 14:1

Lever ratio = 1.3: 1

= Their product is 18:1 i.e the pressure exerted at oval window

This helps in the transformer action of the middle ear (impedance matching mechanism) i.e converting sound of greater amplitude and less force to that of lesser amplitude but greater force

Cone of Light

¾

y Seen in anteroinferior quadrant of the tympanic membrane is actually the reflection of the light projected into the ear canal to examine it

y The tympanic membrane appears as a grayish white, translucent membrane set obliquely inside the canal.

The important landmarks on membrane are:

y Handle of malleus: It is directed downward and backward;

ending at the umbo Cone of light radiates from it Pars tensa is arbitrarily divided into four quadrants by a vertical line passing along the handle of malleus

and horizontal line intersecting it at umbo

Since, short process/lateral process of malleus is least obliterated by diseases so I think it is the most reliable sign in otoscopy.

20 Ans is a i.e Auricotemporal nerve

21 Ans is a, b and e i.e Auriculotemporal nerve; Auricular branch of vagus nerve and Glossopharyngeal nerve

22 Ans is c i.e Healed perforation has three layers Ref Dhingra 6/e, p 2, 3, 5/e, p 4,79

Let’s see Each option one by one

Option a – Cone of light is anteroinferior

This is correct – “A bright cone of light can be seen radiating from the tip of malleus to the periphery in the antero-inferior quadrant”

Option b – Shrapnell’s membrane is also called as pars flaccida This is absolutely correct – Dhingra 6/e, p 2, 5/e, p 4

Option c – Healed perforation has 3 layers

This is incorrect

¾

y When perforation of tympanic membrane heals, it heals in two layers and not in three layers Dhingra 6/e, p 55-56)

¾

y “Healed chronic otitis media is the condition when tympanic membrane has healed (usually by two layers) is atrophic and easily

retracted if there is negative pressure in the middle ear” - Dhingra 5/e p79

Option d – Anterior malleal fold is longer than posterior fold Well! it is not given anywhere that anterior fold is longer than posterior,

but we have to eliminate one option and that definitely is option ‘c’

24 Ans is c i.e Glossopharyngeal nerve Ref Dhingra 6/e, p 228, 5/e, p 241

NOTE

¾

y Pain in the base of tongue is referred to ear via glossopharyngeal N

Lets analyse each option separately.

¾

y Pain from pharynx is referred to ear because it is supplied by vagus & Glossopharyngeal nerves (via pharyngeal plexus), both

of which supply ear also Hence any pain in pharynx can be referred to ear

y Pain from vestibule of nose is not referred to ear because it is supplied by maxillary nerve which does not supply the ear

27 Ans is b i.e It is a protective reflex against loud sounds Ref Dhingra 5/e, p 9-10, 30 Stapedius muscle helps to dampen very loud sound and thus prevents noise trauma to the inner ear It is supplied by VII nerve

(facial nerve) Lesions of facial nerve lead to loss of stapedial reflex and hyperacusis or phonophobia i.e intolerance to loud sounds.

For more details see chapter – physiology of hearing and assessment of hearing loss of the guide

NOTE

Stapedial reflex = Acoustic reflex

28 Ans is a i.e Anterior part of V nerve

The tensor tympani is supplied by 1st anterior branch of mandibular (nerve of 1st arch)

¾

y Greater superificial petrosal nerve joins the deep petrosal nerve to form the nerve of pterygoid canal or also called as Vidian nerve.

¾

y Vidian nerve reaches pterygopalatine ganglion to supply the lacrimal gland and mucous glands of nose, palate and pharynx

¾ Arnold nerve: It is a branch of cranial nerve X which carries fibers that supply sensory innervation to the ear canal

Jacobson nerve: It is a branch of cranial nerve IX that runs along the promontory of the middle ear supplying sensation and

parasympathetic fibers to the parotid gland

30 Ans is d i.e Footplates of stapes Dhingra 6/e, p 5 Fig 1.8, 5/e, p Fig 1.4

See text for explanation

31 Ans is a i.e Epitympanum Ref Dhingra 6/e p449; point 149, 5/e p461; point 90; Maqbool 11/e p13 Prussak's space is the space between pars flaccida, and the neck of malleus in the Epitympanum (see fig 1.4)

¾

y It is the M/C site for primary cholesteatoma

32 Ans is c i.e Roof of middle ear Ref Dhingra 4/e, p 5, 5/e, p 5, 6/e, p 5

¾

y The roof of middle ear is formed by a thin plate of bone called tegmen tympani It separates tympanic cavity from middle cranial

fossa

¾

y Tegmen tympani is formed by squamous and petrous part of temporal bone.Q

Facial recess or Posterior sinus – It is a depression in the posterior wall of the middle ear.

It is bounded by:

Medially – Vertical part of VIII nerve

Laterally – Chorda tympani

Above – Fossa incudis

Importance – This recess is important surgically, as direct access can be made through this into the middle ear without disturbing

posterior canal wall (Posterior tympanotomy approach)

34 Ans is a i.e Facial nerve horizontal part

35 Ans is b i.e Medially it is bounded by chorda tympani and laterally by facial nerve

As discussed in the above question, all are boundaries of facial recess except horizontal part of VII nerve, so it cannot be damaged (Ans 34)

26 SECTION I Ear

36 Ans is b i.e Bulb of internal jugular vein Ref Dhingra 6/e, p 5, 5/e, p 6; Scott Brown 7/e, Vol III p 3110

Read the text for explanation

Promontory is seen in the medial wall of middle ear and is due to basal coil of cochlea.

¾

y Anterior to oval window lies a hook-like projection called the processus cochleariformisQ for tendon of tensor tympaniQ

The cochleariform process marks the level of the Genu of the facial nerve which is an important landmark for surgery of the facial

nerve

39 Ans is b i.e Mastoid antrum

40 Ans is a i.e Mastoid antrum

41 Ans is a i.e Suprameatal triangle

Mastoid antrum is marked externally on the surface by suprameatal (Mac Ewen’s) triangle

For details on Mc Ewen's triangle read the preceding text

Joints of the ossicles are synovial joints

¾

y The incudomalleolar joint is a saddle joint (variety of synovial joint)

¾

y Incudostapedial joint is a ball and socket joint (type of synovial joint)

44 Ans is a i.e Anterior wall Ref Dhingra 6/e, p 5, 5/e, p 6; Scott Brown 7/e, Vol III p 3114 Fig 225.13

¾

y The tympanic end of the eustachian tube is bony and is situated in the anterior wall of middle ear The pharyngeal end of the tube is slit like and is situated in the lateral wall of the nasopharynx, 1–1.25 cm behind the posterior end of inferior tubinate.Q

45 Ans is c i.e 36 mm

46 Ans is d and e i.e Inner 2/3rd is Cartilaginous; and Opens during swallowing

Ref Logan and Turner 10/e, p 227; Dhingra 6/e, p 57, 5/e, p 63

47 Ans is a, c and e i.e Size is 3.7 cm; Opens during swallowing; and Tensor palati helps to open it

¾

y The Eustachian tube/auditory tube in the adult is 36 mm in length (Range 32­38 mm) From its tympanic end, it runs downward

forward and medially joining an angle of 45° with horizontal

y It is lined by pseudostratified columnar ciliated epithelium (cartilaginous part contains numerous mucous glands)

The Developing Humans: Kleith 8/e, p 431-32, Langman’s Embryology 10/e, p 317-323

“Eustachian tube serves to ventilate the middle ear and exchange nasopharyngeal air in the middle ear In children, ET is tively narrow It is prone to obstruction Q when mucosa swell in response to infection or allergic challenge and it results in middle ear effusion”

rela-Ref Gray’s 40/e, p 626

Table: Differences between infant and adult Eustachian tube

Length

Direction 13–18 mm birth (about half as long as in adult)More horizontalQ, At birth it forms an angle of

10° with the horizontal At age 7 and later it is 45°

36 mm (31–38 mm)Forms an angle of 45° with the horizonal

Bony versus cartilaginous Bony part is slightly longer than 1/3 of the total

length of the tube and is relatively wider Bony part 1/3; cartilagious part 32/3Tubal cartilaginous part Flaccid Retrograde reflux of nasopharyngeal

Secretion can occur Comparatively rigid, Remains closed and protects middle ear from reflux.Density of elastin at the hinge Less dense; tube does not efficiently close by

recoil Density of elastin more and helps to keep the tube closed by recoil of cartilage

50 Ans is b i.e Petrous part temporal bone Ref Turner 10/e, p 228; BDC 4/e, Vol III p 264

Inner ear lies within the petrous part of temporal bone

51 Ans is c i.e Cartilaginous bone

Bony labyrinth is an example of cartilaginous bone

52 Ans is a i.e Connects internal ear with subarachnoid space Ref Dhingra 6/e, p 9

Cochlear aqueduct connects scala tympani with the subarachnoid space This is the reason why otitis media can lead to meningitis

53 Ans is a i.e Cochlear aqueduct

Ref Grey 40/e p635; Dhingra 5/e p112; http:// Journalsleww.com/Otology, Pediatric audiology: Diagnosis, Technology and Management

by Jane R Madell, Carol Flexer 2008, p28

Pathways of spread of infection from middle ear

y The non-ampullated ends of posterior and

superior canals unite to form a common channel

called the crus commune.

So the three canals open into the vestibule by 5

y Footplate of stapes covers the oval window and secondary tympanic membrane covers the round window

 Mnemonic : SORT :  Stapes (footplate) covers

57 Ans is a i.e Scala media

Read the preceding text for explanation

58 Ans is c i.e Scala vestibuli Ref Dhingra 5/e, p 11 & 18, 6/e, 9, Tuli 1/e, p 18

Read the preceding text

Important Relations of middle ear:

y Lateral wall – Tympanic membrane

60 Ans is a, d and e i.e Maxillary; Frontal and Ethmoidal Ref BDC Handbook of General Anatomy 4/e, p 32 Pneumatic bones are one which contain large air spaces lined by epithelium e.g.: maxilla, sphenoid, ethmoid, Frontal etc They make the skull light in weight, help in resonance of voice, and act as air conditioning chambers for the inspired air.

Remember

Mastoid is a spongy bone (cancellous or trabecular bone) and not pneumatic bone

61 Ans is b i.e Cancellous bone

Spine of Henle is a cancellous bone because mastoid is a cancellous bone

62 Ans is d i.e Anterior inferior cerebellar artery Ref Dhingra 6/e, p 11; 5/e, p 13 Labyrinthine artery is a branch of anteroinferior cerebellar artery but can sometimes arise from basilar artery.

It supplies whole of the inner ear

Kindly see the preceding text for more details

63 Ans is a i.e Scala media to subdural space Ref Dhingra 6/e, p9, 5/e, p 12

Endolymphatic duct – It is a part of membranous labyrinth (Scala media)

y Aqueduct of cochlea – connects scala tympani to subarachnoid space

65 Ans is b i.e secreted by stria vascularis

66 Ans is c i.e To maintain electric mileu of endolymph

Scala vestibuli and scala tympani are filled with perilymph, whereas scala media/membranous cochlea is filled with endolymph.

Origin and absorption of inner ear fluids

y Tragus Rest of the pinna

y Tympanic membrane – develops from all 3 germ layers (Ecoderm, mesoderm and endoderm)Q

See the text for examplantion

See the text for examplantion

70 Ans is b i.e First pharyngeal pouch and c i.e 2nd pharyngeal pouch Ref IB Singh Embryology 8/e, p 110

The Eustachian tube, tympanic cavity, attic, antrum and mastoid develops from endoderm of tubotympanic recess which arises from the first and partly from the second pharyngeal pouch Since this question is of PGI – we are taking both 1st and

2nd pouch as correct answer but if single option is to be marked, it will be 1st pharyngeal pouch

“Mastoid antrum is an air-filled sinus within the petrous part of temporal bone It commincates with the middle ear by way of the aditus and has mastoid air cells arising from its walls The antrum, but not the air cells is well developed at birth”

30 SECTION I Ear

“Development of the mastoid air cell system does not occur until afterbirth, with about 90% of air cell formation being completed

by the age of six with the remaining 10% taking place up to age of 18” —Scotts Brown 7/e, Vol 3 p 3122

Hence, mastoid antrum which is not complete without its air cells, development is not complete at birth

72 Ans is a i.e Ear ossicles Ref Pediatric Neuroradiology, edited by Paolo Tortori Donati 1/e, p 1362

Mastoid bone not the mastoid process is almost the adult size at birth, while maxilla and parital bone grow in size as head grows

73 Ans is a i.e Improper fusion of auricular tubercles Ref Dhingra 6/e, p 11, 49; 5/e, p 54

y Treatment is excision of tract

Malleus and incus are derived from mesoderm of 1st arch Stapes develops from second arch except its footplate and annular ment which are derived from the otic capsule

75 Ans is b, d and e i.e Eustachian tubes open behind the level of inferior turbinates, growth of organ of Corti is complete by

5 th month and ossicles are adult size at birth Ref Dhingra 6/e, p 12, 57 Refer text for explanation.

Formation of cochlea is complete by 20 weeks & a fetus can hear by 20 weeks

'Scheibe dysplasia It is the most common inner ear anomaly.'

78 Ans is a, c and e, i.e a Bony labyrinth anteriorly; c Sigmoid sinus posteriorly; e Superior petrosal sinus superiorly

“Trautmann‘s triangle is bounded by the bony labyrinth anteriorly, sigmoid sinus posteriorly and the dura or superior petrosal sinus

79 Ans is c i.e Aditus ad antrum – Mac Ewen’s triangle Ref Scott Brown 7/e, Vol 3 p 3120

Let’s analyze each option separately